Limit poker will allow you to wade into more sites for bonuses, as you can play at a higher table stakes level, and often meet raked hand bonus requirments more easily. Because each bet is based more on pot odds (a rough explaination) quick decisions can be made and more tables played at one time.

That being said, more of the folks around here play NL (it used to be part of FTR's description that it was about NL). It is currently the more popular form, so there are more fish, and at low level play one's bb/hr rate can be relatively high.

Even the differences between tournament play and ring games are significant.

I learn something every time I swich to a different form a poker - limit, Omaha 8, 7CS -- which I can bring back to my usual game. But it makes sense to focus on one type.